Carburetor



Sept 15, 1931-- M. R. WOLARD 1,823,017 f Inventor. Meri Fi. Wolford tay/Ma MMM Sept. `15, 1931. M. R; woLFARD 1,823,017

' CARBURETOR Filed July 17, 1928 4 sheets-Shen E6 Flg-4-3g7 EL;

34 373 aga lm/enfor.

M. R. WOLFARD Sept. 15, 1931.

CARBURETOR Filed July 17, 1928 4 Sheets-Sheet 3 M l/ 'B m Il o un d e I@ 1 ,vl m 6 H 0 n e w ,n m 4 m m. e l 0 I H l.-. m s. I H l 'Ill/111011111111111all Anya O O mw W ma Merl by fawn wx!" Sept. l5, 1931. M. R. woLFARD 1,823,017

GARBURETOR Filed July 17, 1928 Fig. IO.

4 Sheets-Sheet 4 Patented Sept. 15, 1931 UNITED STATES: PATE Nr lorries..."

nani. n wom-ARD, or CAMBRIDGE, MASsAcHtis1rrrs.v AssIGNon 'ro :CHARLES F. Horn- WELL AND HELEN c HoPnwELLf'A .ooPA'RrNEBsH'IP DOING WELL nnormms, or wATEnTowN, nrAssAontrsEmrsv i BUSINESS AB HOPE- clAnnUnn'ron iy-Appnmioii nica my 17,v

This invention relates to improvements in carburetors and provides a simple design for effectively proportioning the mixfturesv at all times through unit-controllingy means with 5 means for temporarily enriching the mixture for starting', together ivith inherent temper? ature' and Vbaromctric regulation whenever necessary,4 and .further eliminates .thfn `ls sity of accessory acceleration,devieesQ u ,l n,

A principal object thereof vis to'pr vide. simple design of mixture-proportioning parts.l so positioned land correlated ,thati'i"'s1ngle'l or unit control will produce a substantially proportional change in the fuellair ratio'- during idle and light load operation aswell as under heavierv load operationll In the operation of an internal combustion engine a. rich fuel-air mixture is required at cold starting and as the engine warms up zo theratio of fuel to air must be-decreased for economical and satisfactory operation until,- normal operating temperatures are reached.

Also during normal operation at low atmospheric temperature the ratio of fuel to air must be greater than at high atmospheric4 temperatures. i

Furthermore, while operating at any temperature the ratio of fuel to air'should be gradually increased below about half load as the load decreases to idle operation of the engine. In order to produce this last result a plurality of passages for the fuel or for the 'fuel-air mixture have been employed in previous carburetor constructions, but have been so related to each other as to cause an interruption or reversal of flow through cei'-, tain of said passages as the operating load changes, thus causing a temporary storage of a portion of the fuel. This results in a leaning down of the mixture in proportion to the ainount of storage and requires an (wer-enriching of the mixture, to compensate for the lag in flow, in order to secure proper operation of the engine.

Therefore, no singleor uuitcontrol has been, or can he, employed in such carburetor constructions as is required to satisfy the two previously stated conditions, namely,.to proflum.- a proportional change in the. Jfuelair ratio throughout the entire operating :baati A. nurture" oivx'from 'therfuelfinlet and thererenal, serial No. aea,i'zli.f. l l range f r im lid1e`load either during cold starting and warming up of the engine, ordnung changes' in atmospheric temperature. f ,l I-,'Anpfobectofwthe present invention :is to proigdexmfein'sjor producing a. proper; prov porti' o'iiir'zlgof,thel ,nel-air mixture'ili c'l'nf ,-mtlij meaiiselfecting uninterrupted beyond "der Vall' normal'conditions ofperationlffrl dleto vfull loa'dt I 1 j vfl'lie'lteim funiterrupted iirture-low as usedherein signifiesfa continuous C 'arryin forward of "the 'fuel 4in the air fromthe fue inlet Without cessation or f diminution and avoiding'a lag inthe flow of anyrconsiden able Vportionof the fuel` from'the fuel inlet andtherebeyond, such vasl would be caused by a temporary'V storage or reversal ofV flow of any portion of the fuel between the 4fuel inlet and the carburetor outlet. v Thus uninter# rupted `mixture flow insures continuously'an undiminished flow of fuel through, the carburetor and j avoids the necessity 'of overenriching the mixture to compensate for any reduction'in the fuel delivered to the carburetor outlet caused bythe storage or the reversal of flow of fuel.

This is accomplished in a preferred embodiment of the invention by placing the fuel-inlet in the air metering section of the mixing passage and providing means maintaining a low, predetermined flow of fuel through the fuel inlet irrespective of the suction head in the air metering section, in combination with the positioning of the throttle valve so as to maintain uninterrupted mixture flow beyond the fuel inlet.

A further object of the invention is to provide unit-controlling means operable to vary the relative proportion of fuel to air supplied tothe mixing assa e.

Another obJect o the invention is to provide means for ent-raining the fuel in the air in such a positive and definite manner asto. eliminate the necessity of providing special means for supplying additional fuel during the acceleration of the engine, such as accelerating wells, fuel pumps, etc.

Another object of the invention is to prO- 10| of operation, with a degree'T of precisionfheretofore' un att ained.

A further object of the invention is to provide barometricmechanism operable, preferably in f conjunction with the thermostatic 1o mechanism, still further to refine tlieprecision of the fuel-air ratio, thereby adapting the carburetor for use in varying altitudes. v f

Another object of the invention is to provide means for continuously supplying fuel at a low, predetermined head to the fuel inlet,

preferably located in the air metering'section, to supplement the rate o fvflow induced by the suction head in the air 'metering sec,- tion acting upon the fuel inlet during normal operation of the engine from idle to .about halfv load` injcombination with 'a throttlng valve in the mixing passageihaving its lowe'r eiidportion below and beyond -said'fuel inlet operable to maintain an uninterrupted niix-` ture flow from themetering 'section t'ofthe engine during idle and light load operation.;

A further object of the inventionis to provide a depression in the mixing passage 'be-.f

yond and below andin proximity to said fuel inlet to receive fuel which may ilow by gravity from said inlet and a throttling valve having its lower portion extending into said depression operableduring idle and light load` operation to maintain an vuninterrupted mixturellow. v Y

. A further object of the invention is to po s1r-v tion the throttling valve 1n such proximity4 ."to the metering section that when approaching wide open position a slegm'entzof-said 402 throttling valve will proj ect into themetering secti0n to restrict its effective area, thereby increasing the ratio of fuel to air.

A further obj ect of the invention is to provide a fuel reservoir surrounding said fuel inlet having means for maintaining a liquid level in said reservoir slightly above said fuel inlet, with the wall of said mixing .passage extending above the liquid level in said reservoir adapted to prevent loss of fuel when the. engine is not in operation.

Another object of the invention is to provide a reservoir surrounding the fuel inlet and communicating therewith having means for supplying fuel to said fuel reservoir 1ncluding a regulating valve and float sections 00 sufficiently large and substantially constant multiplied force to said regulating valveirrespective of the inclination-of said reservoir, whereby the fuel in thl'e reservoirv will be maintained with only small variations in C5 height above or below a predetermined level duringiidle and light load operation of the engine.

These and other objectsand features of theinvention will more fully appear `from thc following description ,and theaccompanying drawings, and will-be particularly pointed out in the claims. :Illustrativeembodiments of thevinvention are shown in the-.accompanying drawings, in

. which,

Fig. 1 is a view mainly in-.vertical vlongitudinal section of a lpreferred embodiment of theinventio'n in which the fuel 'level is maintained slightly Yabove the fuel inlet to the mixing passage to produce a continuous flowing head; y

Fig.` A2 is aplan viewof the same; 3 is `a detail view. 'illustrating the connection between the .fuel .valve and .the thermostatic device for; controlling .thev same:

. Fig., 4 is a view,',par tly inend .elevation and partly inA yerticalsection, showing par` ticularly the mechanisinfforreglating the level= of liquid ,inthe ryaservoira Fig. f5's a. detail view, `mainly n-vertical section', illustrating a :modi-fied -f orm of the invention 'comprising an automatic throttling valve for maintainingmninterrupted flow of-mixtu're during idle and light load operation with a ,usuall type of throttle valve;

Fig. 6 is a :detail view illustrating a modiiiedfarrangenient of fuel inlet and valve;

Fig. 7 Ais a." view, mainly in vertical section, illustrating` another embodiment of the invention in which a continuous flowing head is produced in a different manner; 4

Fig. 8 1s a` horizontal ,sectional view of a portion of the construction illustrated inl Fig.

7, on line 8.8, Fg."2';fr Y

Fig. 9 is a detail plan view of means for locking the fuel valve cage in adjusted position- Fig.V 10 is al graphic illustration showing curves based respectively upon theload per-` centage and fuel-air rati-o and illustrating a comparison between the action of the usual suction head and a flowing head, and the advantages attained by the flowing head of the present invention; and

Fig. 11 is a graphic illustration showing curves based respectively upon the load percentage and fuel-air ratio and illustrating the manner in which the present invention maintains a mixture ratio within the desired ranges both of maximum eliiciency and maximum power.

The carburetor illustrated in Figs. 1 to 4 of the drawings comprises a casing l having a mixing passage consisting ofA an inlet section 2 and an outlet section 3, preferably relatively inclined to each other,- forming at their junction a depression 4. The mixing passage is so formed as to provide a restricted portion of an air metering section 5 of reduced area within the inlet section and preferably infront ofand inl proximity to the depression 4.-- Such 'air` metering section of restricted area may beprov-ided in .any suitable'manner. In the :construction illustrated .'he'reiir'ailler 6 is securedto, or formediinh stegral with, the upper portion offthe cylindiical wallof` the casing andpresents a flat :"'lowenfaee which in conjunction with the lowner wall' of the inlet section providesr a sub- :stantially semi-cylindrical .metering section lofthe-desired restrictedarea; A fuel inlet 'fleads to the airmeterin'g section of the mixr'ing passage.I If the minimum area of the a-ir .il'netering' section -is-atg the fuel inlet, ,the quanmaintaining 'the liquidiat the 'proper height above the fuelinlet, las 11- l'ustratedi` in the present invention., i comprises fa'res'ervo'ir Shaving therein cylindrical float sections 9 Aand l() symmetrically 'positioned relatively :to the fuel inlet, with' lever mecha- I'nismf intermediate of the float section and valve operable to transmit a suliiciently large fand substantially constant multipliedforce to theV regulating valve regardless of the in- -height ofthe elfi nation of the reservoir thereby to maintain vv'itlraV proper ldegree of precision 1n 'the fuelY level during :idle and light 1 loadfope'ration'. f

In' ,the particiilar construction illustrated the lever mechanism comprises ayoke 11, the arms 12 of which extend to the lower portion of and are attached to the float sections 9 and 10, while the body' ot the yoke extends substantially horizontally and is pivotally mounted at its cud upon a pin 13 carriedby lugs 14 extendingr dmvnwardly from the' 'casing-1.'

A. lever 15. having at one end a knife edge 161 engages the yoke 11 and at its opposite end is pivotally mounted upon a pin 17 carried by lugs 18 depending from the casing 1.

rlhe casing 1 provided at one side of the "passage 3 with an upwardly extending boss '19 bored vertically to provide a fuel supply passa-ge 2O leading to the reservoir. The upper portion of the wall of the bore is screw threaded to receive the complementary screw threadsv of a valve cage 21 which desirably has an angular or hexagonal enlargement 22 at a distancefrom its upper end. The upper end of the portion of the lvalve cage is provided with external screw threads 23 to receive a coupling 24 for the end of a supply pipe 25.

A= valve seat member 26 is interposed be- -stickingof the valveupon its seat.

Ltween the coupling-24 and the upper end of the valve cage 23 and comprises ahead which rests upon theA upper end of the cage and a downwardly extending cylindrical portion 27 which desirably is pressed into the upper end of af-vertical cylindrical passage-2810i'I the valve cage. The valve member has'a vertical 'central bore 29, the lower end of the wall'of which istapered to. form aV conical seatfcomplementary to the conical endlof a regulatfing valve 30'which extends axially ofthepas- 'sage 20-in 'the' .b'os'sand of the passage. 28 of 'the valve cage.' The lower end ofthe valve l30 lis provided with a reduced extension 31 ywhich passes 'through `a suitable aperture in the lever 15 located in proximity to the pivot 17 of said lever and'fthe shoulder 32 at the balseoffthe extension z31 desirably isI slightly 'rounded "and fso=^eonstr1icted that it :contacts Awith the'l'ever y15 slightly-belowthe pivotlZ ofthe 'lever when the regulating-valve isnor- By reasonof this construction no sliding contacts are= present vv'which 'wouldinterfere -witlr the free movement'of'the valve;1r Furv th'e'rmore, the verticalswmgmg movement of the 'lever .15, even thoughfslight, transmits a-suflieient lateral movement toc the-lower end of the valve `30"'fwh-ichwill prevent the AAs the distance between the fulcruinof'the lever'li" and ,the 'point of engagement therewith by the valve-'30 is very much shorter than the distance from such point of engagement to the v4knife `erdg'e'd' at ther endv of the lever which engages theyoke'and as the distance between vthe 'point Iof" engagement' ot 4the knife edge 16jis mu'ch'closer to thepivotal support 13 of the yoke than the distancefr'om the knife edge to the 'center of thefloat sections, a very substantial'multiplying leverage is interposed between the float sections and the regulating valve which insures delicate regulation of the height ot' the fuel level in the reservoir during idle and light load oper' ation of the engine. This multiplied' leverage necessitates a substantial drop in the position of the float sections, (about BAW) when the engine is operating at full load in order to permit a sufficient lamount of iuel to flow into the reservoir.

By reason of the adjustability ot the valve cage 21 within the boss 19. the vertical position of the valve seat may be varied to establish the liquid level in the reservoir at a pre`A determined height above the fuel inlet.

l Positive lockingr means desirablyv are provided to retain the valve cage in adjusted position. Any suitable means may he employed. In the present construction a. locking plate 3? is provided which has an aperture therethrough lhaving walls complementary to the walls of the hexagonal head and extends'laterally therefrom over the upper end 34 of the boss and rests thereupon.

'ilheexternsion ldesirably iis iprovded with ra'.pluraltyof apertures-35 and 36tto .receive a :screw 8.7 :adapted .to beseated A,inni suitable socket :in the upper :end 254:v of th'eboss.

A11 important feature ofthefinvention 'as (illustrated =in `4`Figs. l lto 4 inclusive Yconsists 'tion Whih is .fin the general formof abutter- :Hy valve, securedfbysuitable :screws to .'the iattened :portion offa shaft 40 which extends transversely v=of thezoutlet -passage and is lrotatablyzmounted in th'e walls-offthe casing.

The Ashaft 40 may lbe provided with asuitable -arm 41 adaiptedtozbeconnected to ftheusual tln'ot'tle control -fuponthe instrumenty board.

The upper-,end :portion d2l 'of the valve 39 desirably is substantially atniand'fwhen 'in closed position, :as-:illustrated in fFig. 1, Icom- .-fpletely'fcldses'ftheupper .fppontionof thefoutlet upassage --The *lower-endportion .43 ofithe valve 39 ,desirably-isjrnade somewhatk thicker vnot thevoutletpassagefand when Ithe valve is `J-.thanwthe upperfportionfand -is curved-toward f approximate parallelismwiththe 'lower wall closed is spaced slightly-'therefrom'and 'eX- tends rintolthe depression 4 which,as illusftrated iin-Fig. 1l,- isfa-t the junction-or-thefrela- 'tively inclined inlet randoutlet sections lof the-.mixinggpassage The space 144 between fthe' lower rend ofthe valve *43 and the' wall of (the-outlet' passage ris suchas to :permit #the passage .of only suli- 'cient ffueLair min-ture to causethe engineI to :operate ysatisfactorily `on idle, .and ithe pa-ssage .between the rlower fend .portion-of ythe val-veand-the casing increases gradually 'from the .lower vend .of the valve --for .a .short4 distance ltherebeyond in orderto reduce the swish produced bythe-very 'high velocity andeffective breaking-'up of the-.fuel whichfisdrawn -throu'ghth-is :passage by 'the suction ofithe engine when running at lightload.

By reason ofthe-fact that luel ,is delivered through the fuel-inlet under a llow-.flowing head maintained ,irrespective -of the suction head in the metering section 'of the .mixing .passage,"the suction h'ead inthe lmixingipassa-ge, acting .upon the `fuel inlet, 'in addition to this low flowing head, will produce a properly proportioned mixture during 'idle and normal-operation of th'eengine [up to-and :somewhat *beyond half load. This" properly proportioned mixture -lows-uninterruptedl-y,

(without requiring additional energy from the air-stream -to lift the uel,) into'the depression 4, and the throttling valve, which projects -into 'the ydepression 4, maintains uninterrupted '.mixture flow during :idle Vand light loadfoperationfas well as during :heavier zoads.

: fwhere maximum ation. l Y

While @the f mixture. ith-nsv obtained may .be

llhetlrrottlin-gfwailfve 39|.-desirabl1yfis soiposiftiuned that when fitis rmoved toward wide lropen-:positiondhelower end fwill intersect l'the rplane fot :the I'air Imetering :section 5 `ais the fthrottliug valve moves trombeyond half open. ftoward full epenposition. As thethrottling valve moves `from 'beyond-rhalfopenfposition -ftowazrdiu'll open "position, t'he 'lowerportion :of the `:valve'swings Ainto lth'efair metering @sectionofzthe Jnixingpassage yinzsuhza man- -'ner that the thickened lo-wenend 'portion' .of rthe .valvefreduces 'that afreawof the :airimetersectionwhichis above the fuel -inletand ,'normalto the inclinationzof thefinlet section. .":Dh-isreduction of'thefarea-of- .the air metering Asection increases the suction fhead at the -fuel "inlet zandI v.consequently increases .the ratiowof `'ruel--to airfa's wide open throttlerisapproached power is therprime considerjrichenstharn that required Ifor 'maximum-cioiency, rit-is desirablerthat 'sucht mixtures'hall be supplied to produce maximum power .as

.rtlie' fthrottle lapproaches full lopen position which Yissonly requiredduring` a :comparati-ve- -ly-shortitime vrelativelyto the total time dur- :inlg the 'normal' operation of 2automobileeng'ines. A

A ,fp-referred .mechanism tor changing the I'fuel-air--ratio ove-rytheentire range fof Tload "from iidfle to liulliload fof the engine, ywhich is .illustrated fin rFigs. 'l-to Itinclusive, comfprises :a valve 45, fpreferably of cylindrical form, which 'extends 'across the metering sec- -rtion and i-s:slidably mounted'i-n .the fuelinlet -'6 'with the cylindrical up-'stream wall 46 complementary to the cylindrical :up-stream wall of :the inlet .poi-t. Tfhe'lower pportion 'of the valve -is chamfered or'cut-awayu-,pon the downstream side preferably to present a flat faced? cut-at an acute angle tothe of `the valve,'so that -byraising and lowering the valve-the effective area-of the outlet fwill he increased =ordecreased.

In vusual carburetor constructions o-this type, in which a needle valve is employed, 'the Ineedle valve isguided-in the wall' of the -fmixing passageopposite to the fuel -inlet and 'fis provided vwith :a -screw threaded Yadjust- !ment. Wheretheguide for :the need-le valve :is so remote `from fthe fuel inlet relative "to 'fthefdi'stance between fthe valve .and lthe wall 'of Ithe inlet, :rotative-adjustment is likely -to bringthe valve into contact, .ori-n -closer maintaining a Wa'll of-the valve in-light,but

positive engagement with the complementary A:wall -of 1.the indet, thereby avoiding zerratic soV changes in the fuel-air ratio with small 'adjustments in .the positionofthe valve.

In the construction illustrated in F1gs..1

to 4 inclusive, 'the up-stream wall of the valvef is maintained in contact withthe complementary wall of the inlet section by an inclined strut acting upon the thermostat which regulates the posltion ofthe valve in response to variations in temperature in the `mixing passage.

' The cylindrical section of the needle valve, which crosses the mixing passage, merges into astem of considerabl larger diameter, the

lower portions of the ower end of the steml being cut away to present parallel fiat surfaces 48 and 49witha` registering notch 50 upon the down-stream side vwhich presents a shoulder 51 adaptedtobeengaged by a thermostatic contro ling member. v

The preferred form of thermostat shown 'in Fi 1 comprises 'a strip of preferably bi- The ,thermostatic strip at the opposite endof the arm 52 isbent at a substantially rightv angle to present a vertical section` 54 which inturn is bent to present anotherlright angle turn 55 Vand is bentdownwardl'y therefrom towardthe`arm 5 2 to -ermit -itto be con- .veniently aieinbled wit in the mixing passage with the end 56 of the arm-desirably extending' horizontally in .substantial parallelism with the arm 52. The thermostatic member is pivotally supported within the right angle'bend 5'5 by a strut' 57 which isv plvotally mounted at its lower end upon a.

pin. 58 and extends upwardly and at an incliiiation away from the vertical axis of. the valve and engages the thermostatic member Within the right angle bend 55.

` The end 56 ofthe thermostatic element is adjustable by means of a rod 59 which is reciprocably mounted in the upper wall of the casing 1 and at its upper end is engaged bv or attached to a device 60, such as a sylphon bellows, responsive to 'changes in barometric ressure, the upper end of which is engagedJ by an adjusting screw 61 which is adjustably mounted in the arm 62 of a bracket 63`which is secured by suitable machine screws 64 to the casing 1.

Elastic means desirablv" are provided for forcing the valve upwardly to maintain the shoulder 51 of the valve stem in contact with the under face of the arm 52 ofthe thermostatic member. As illustrated in Fig. 1 this is accomplished by a spiral spring 65 which extending upwardly from the casing having one arm 7 O. extendin beneath the pin 4rests upon a shoulder of the casing 1 and engages at its upper end a pin 66 extending transversely through the upper end of the Manual mea-ns may be provided for .temporarily opening the valve during cold vstarting of the engine. Such means may be in the'form of a bell crank 67 which is ivotally Asses` 69 1 and mounted upon a pin 68 carried by 66, with the other arm 71 o said bell crank connected by a cable Ior rod 72 with suitable hand operated means conveniently located upo'nfthe instrument board of the' automobile, (not shown).

A light engagement ofthe needle valve I with the com lementary wall of the fuel -inlet is maintainedbythe pivotally mounted strut 57 'which inclines away from the vertical axis V,of the valve and engages within the right angle bendl 55 of the thermostat, i

'thus' holding the end wall of the slot 53 against the base of the notch 50 in the valve i stem. and exerting a gentle pressure tending to hold the u -stream wall of the valve in contact'with t e Ycomplementary wall of the inlet and also holds the valvev in contact with' anupper bearing'inthe casing. I

The position of the valve-46 may initiall adjusted by-actuation' of the screw 61 whic actin through the end 56 of the re- 'turn bend ofthe thermostat, serves to force the arm 52 downwardly against the tension of the spring 6 5. In the operation of the device upon cold starting the operator by pullin upon the and thereby raise the valve46 againstthe elasticity of the thermotatic elementsufficiently top rovide an additional fuel sup- L Ily during the cold startin of the engine.' yl reason of the fact that lt e thermostat is formed as a return bend and composed of two substantially right angle bends, an increased iiexure is attained as theexure at each right angle bend issubstantially equal to that which would be attained if the ther-- mostat were mere'ly bent into U-sliape.

' A modiiied construction is illustrated in Fig. 5 in which the mixing passage comprises relatively inclined inlet and outlet sections 2 and 3 with 'a depression 4 at the junction ythrottle valve 74 desirably is of the butterfly type and is secured to ashaft 75 extendmounted in the walls thereof suiliciently below the axis thereof to present a larger area above the pivotwhich is subjected to the suction of' the engine than that which lies below the ivot. `The lower portion 78 of the automatic throttling valve is of sufficiently greater thickness, or is so weighted, as totend to maintain the valve in closed position.

i The relative weight of the lower. portion of the valve should be such as to maintain the valve ractically in its closed position until a suction head of predetermined` value is reached. Experiments have shown that a suction head of ei ht to twelve inches of water will be su cient to give excellent atomization of fuel below the lower edge of the automatic throttling valve. The contour ofthe lower ed e of theautomatic throttlingvalve shoul be substantially as heretofore vset forth with respect to the embodiment of the invention illustrated in Figs. 1 to 4 inclusive.

Another form of fuel inlet and regulating valve therefor adapted to avoiderratic flow of fuel from the fuel inlet, with changes in adjustment, is illustrated in Fig. 6, in which a conduit 79 is provided to communicate with the fuel reservoir, with a. lateral aperture 8O therein which communicates with an inclined inlet passage 81 leading to the air metering section above and in proximity to the depression 4 at the junction of the inlet and outlet sections as heretofore described. In this construction the regulating valve is in the form of a needle valve 82 which slidably fits within the upper end portion of the conduit 79 with the tapered portion 83 of the valve extending across the aperture 80. The needle valve 82 desirably extends across the mixing passage and may be controlled by the mechanisms illustrated in Fig. 1. Inasmuch as the needle valve 82 is provided with a bearing 84 near the point of fuel control,it is practically free from lateral movement relative to the .surrounding wall of the inlet and it is so positioned that the flow of fuel is unaffected, by theeurrent in the mixing assage.

Another em odiment of the invention as illustrated in Figs. 7, 8, and 9, comprises a casing 85 havin an inlet section 86 and an outlet section 8 with an air meteringsection 88 therebetween of a predetermined fixed area. As illustrated an ai'r metering section of reduced fixed area is formed byA providing a filler 89 having a. Venturi passage therethrough. In this construction the res- A is provided with a downwardl ervoir having a wall .90 preferably symmetrically surrounds the fuel inlet and is mounted upon or is integral with the wall of the casing 85. In this construction the reservoir communicates through a small orifice 91 located near the bottom of the reservoir with a vertical inlet conduit 92 in aboss 93 the central portion of which extends upwardly a short distance above the fuel level which is maintained infthe reservoir. The u per end of the passa e 92 desirabl is provided with a sleeve 94 orming a fue inlet the area of which is controlled by a valve 95 which is slidably mounted in said fuel inlet. The peripheral wall 96 of the boss desirably is of oblong form, as illustrated in cross section f in Fig. 8, and extends upwardly into engagement with the under face of the cover 97. A suction passage 98 extends upwardly from the inlet section, thence horizontally across the fuel inlet, and thenceA downwardly, and is so branched beyond that one branch 99 communicates with the outlet assage beyond the throttle 100, while theot er branch 101 communicates with the mixing passa-ge at the metering section 88 thereof. The cover 97 extending boss 102 which is located immediately above the boss 93 and in co-operation therewith lprovides a restricted passage 103 forming a metering section in the suction passage at the fuel inlet 92.

Desirably a sleeve 104 is placed in the portion of the suction passage beyond the restricted passage and is provided with a restricted opening 105 communicating with the branch 99 of the suction passao'eV which leads to the outlet section beyond t ie throttle 100. The lower end of the sleeve 104 de-r sirably extends through the wall of the casing and seats in a. recess in the filler 89, thereby holding the filler in place. The filler 89 desirably is provided wlth a transverse slot 106 which extends through a considerable arc of the upper wall of the filler 89 and the filler desirably is provided with a segrrr'flntal boss 107 in front of the slot 106 forming a shield at the end of the suction passage which connnunicates with the air metering section.

It has been shown experimentally that a shield placed in this position increases the suction head in the restricted passage at the fuel inlet relatively to the suction head in the air metering section as the engine load increases' beyond half load and consequently increases thc amount relatively roportional of fuel delivered to the metering section during heavy loads as compared with the amount delivered during light loads presumably for the reason that when two currents of air flow into each other substantially at right angles, and one of said currents is considerably larger in volume than the other, it will tend to cut off the proportiti tional "flow from' the smaller passage 'when' which' have a: chaanfered` in1et,' becausev it is i 10' a Well-demonstrated. fact that: the discharge lcoeiicient offsuch orificesincreases gradually and :very .substantially as;.tlie= Isuction head increases. f: E'

In the embodiment. ofthe invention shown in Figs. 7 Sand 9 this isv accomplished by 'providing 'the Asmall orifice L91 ,ati thebottom ofthe conduit=92 with a'chamfered inletand the-fuel inlet '94'with-a chamferedr'ivalve.

-In the construction illustrated in lFigs.w7,'

`r`8 and-9, it is also imperative toiprovide'for 1 maintaining the -liquid leveliin the fuel reservoir slightly below the rfuel-inlet 94with1af degree; :off precisionlihe'retofore '-unattained duringf idleand l light load operationsi iwf In the particular construction illustrated substantially the same principle is employed as that illustrated in Figs. 1 to 4. Float sections 108 and 109 are symmetrically disposed relatively ito the fuel inlet 94v andare vconl,nected respectively tothe arms 110 and'111- of a yoke 112 pivotallymounted at its end upon a pin 113k in arhollow extension 114 of the wall `-of-the fuel reservoir-:1 The extension 114 is provided fwithranl upwardly extending boss 115 which is bored vertically to supply a fuel -passagezllG `:leadingt the reservoir. The? upper portioniof thee Nva-l-l of tlie bore is screw threaded to'. receive complementary screw threads ofa valve cage 11'7 i which desirably has an angular orhexagonal i enlargement 118 ata-distance from its upper end.`l i fr In the construction shown in Fig. 7 the' cover 97 is provided'with a lV-shaped notch 119 adapted to fit adjacent faces 'of the hex'- agonal enlargement 118 'of the valve cage,

thereby providing means -for locking-'the valve cage from rotationwhenit has been adjusted at a predetermined height. The upper end portion of the valve cage is provided with external' screw threads-120 to receive a coupling 121 vfor theend ofthe supplypipe l122. Avalve seat member 123 is interposed between the coupling 121' and the Aupper end of the valve cage 117' and coniprises a head which rests upon the upper end of the cage and a .downwardly extending cylindrical portion 124 which desirably is pressed into the upper end of the vertical cylindrical passage 125 ofthe valve cage.

` The valve member has a vertical central bore 126, the lower end of the wall of which is tapered to form a. conical seat complementary to the conical upper end of a reguvlating valve 127 which extends axially. of

tliepassage .125 of thevalve .cage and of the bore 116. -The lower end of the valve is provided With a reduced extension 128 which" passes through a suitable aperture in the yoke 112 in proximity to the pivot 113 of saidi position of the valve seat may bc varied toestablish .the liquid level -in the reservoir at a predetermined height slightly belowthe fuel inlet 94.V In this construction `the valve'cage will'be locked in adjusted position' when. the cover'97 of the reservoiris placed in'aposi- .tion upon'the top of thea'eservoir'and se cured lthereupon'by.'suitable'fscrews.'; i

The effective area ofthe fuel outlet is=reg ulated .by the valve 95 Which'desirably is of cylindrical form slidably mounted in a bearing in the boss 102 .and extending across the metering section.103 ofthe suction passage into the fu'el'inlet 94. The lower end of the valve is chamfered on the down-stream side to present a flat face 130 extending at an acute angle to the axis of the valve. Preferably,but not necessarily,y as illustrated in Fig. 7 a'sleeve 131'is forced into the upper end of the inlet conduit 92 and the inner wall of the sleeve is complementary to the cylindrical up-stream Wall of the valve 95. The effective areaI of the -fuel'outlet may be varield as required by'vertical adjustment of the va ve. 1

In the construction illustrated a spiral spring '132, which is seated upon the cover, surrounds the valve and abuts at its upper end against a shoulder upon the under side of an enlarged portion 133 of the valve. A plate 134 is clamped upon the upper face of the enlarged portion of the valve by a nut 135. The plate 134 is engaged by the head of an adjusting screw 136 which is located in proximity to the valve 95 and in parallelism therewith and engages a screw threaded aperture in a boss 137 upon the cover. By reason of this construction a leverage is exerted by the spring 132 against the head of the adjusting screw 136 which maintains the cylindrical 11p-stream surface of the valve in constant engagement with the complementary wall of the inlet.

In the normal operation of the invention as above described, during the idle operation of the engine, with the throttle valve 10() in approximately closed position as illustrated in Fig. 7, the suction of the engine produces a partial vacuum in the branch 99 of the sucofth'e adjustability of the valve l-cage 117 withinthe bossll, the verticaly llwith' the fuel-airmixture draw svszigi-'adually opened from idle` tionpassage, thereby inducing theflofw ofruel through the inlet 94 which mixes Withl the`` airiir thesuction passageandfpassesthrouglr the i restricted; aperture BA and branch-'3 9.9;-tof

5`thef engine; i During such idle-operation air is al-so causedzto flow'upwardly throughi the slot' l06in:;theiller'89iinto the lowerend '0f-"ther, branch 101'. of the` suction; passage and( vout; through the restrictedaperture ltominglu n through the; suction-passage.- a 1 l The area of the restricted passage lOaini thel 'sleeve l04 .is soproportioned relative-'to the-area'fothe'lower end` of thebranch 19h liifleadi-ng to the' air' metering 'section '88 fin the n mixing passage, and fto thexarea-of the metems ingr-section: 103 of thesuction' passage,=that the-suction produced; in the `metering sec tion 103- Will maintain .iaflow: oa fuel'fromx tlie'."4

fueli inlet at alow flowinghead sufiic'ient' toi produce satisfactory operation on.Y id'le. f

It is Well known that Whenairl is: drawnA through anv oriiiceo 'restricted area,`;suchl as the: aperture 105,11 "maximum fflow through.v

sthat orifice will' beinduced when the pressure in;- thev passage 993 is reduced:v to approximately' fifty-three per cent of: thel barometricr pressure. However, when.' fuel is Y entrainedi in, thefair' drawn-'through suchs-orilice, this sliflimiting; flow will be reached at a somewhat- 40rjloadoperation up to about ha'lf load.:

The flow oi air through the slot. 106 from: the metering section of' the mixing-passage toward the aperturewill be gradually ree' duced.' as the throttle valve is opened' andrai 45," positive downward' fiow o'ffuelt-air mixture' will be induced through the slotv 106,1anehintoy the metering section 88 of the mixing'passageif As the suction head in the metering'section 88 increases a gradual lessening' oi flow to 5M Wardl the restricted opening105`isproducedl,

then a' gradually increasing positive flow. downwardly through the slot 10G is .produeedf which builds up f raduallyl from idle an.: increased suction at the metering sectionl of ijthe suction passage, thus inducing a greater flow of fuel from the fuel' inlet 94. By'rewf` son of this construction the miaxturel'f'lbw' is continuous and uninterrupted from' the metering section of the suction passage andi mtherebeyond.

One o'f the principal objects of thepresentrginvention is to provide mea-ns for'delivering fuel through the fuel inlet continuously at a low, predetermined rate irrespective of mls"the suctionl headi in the metering seetiorr7 withl. .,unit-controlling:4 means: operable' 1: toi change theivratio. of; fue1.,to:airsupplledtof,

the mixing passage; in conjunction with;

mechanismA arrangedto -maeintainf uninhen rupted min-ture` ilowefromfbeyond' saidf fuel inlet.v .f 1% f' 'i Unit control isi-accomplished by regulating l thel amount.: o-.fiuel delivered v through the.; fuelinletz. Ih, the; embodiment ofr the: in-f ventiorr villtustirated' in,A Ill'igs;t 1- I to 4; inclusive thezarea of ;the;.fuel=. inlet is;regulated.y Inthei .embodiment voli ',the; invention disclosed;- in Figs. 7, 8, and 9, the suctionv head` acting at: thel vfueliinleu?is;`1.-'e'gulated t lim thei particulan` -zconstnuctiom shown" in F 'A f7 this; is; acoomplisheds byg providing' l ai che -uallvef or' v valves? for kzontnollin'g." the 'admission' ot; airinto `theinlet section .of fthefmeteniln 'pase i sage. (Dfbuio'usljy,1 zwlie'ni `,the choke y nef or valxies are; ini partially; clbsedi. position ithel suction Fin: 'the inlet,` section'.`V Eis.'v Iuuchi greater f thanwhen: the choke lm'a'lve Bisi nxoneixwiidely: opeirandafthe suctinniheadaapplied toithefinsllet section'lwilli-inoreas prepbrtionaiielyebothi tliei suctio'ni head-at the .meteriugfesecti'om '88 and` ati themetering section: 10.3' ofthe suction passager?? i i il I' :Inl -thei'emhodimentot the invention; illus*y trated Iini f 7i means i arefprovided 'fbrr sup plying bothihot: and Gold( ain'tovhecarbubetor'- with thermostaticaxllycontrolledl valves op` erable tovaryythewsuctin: head1 in 'the' inlet;` sect/iorrfduring'the-warming up-:of'the 'engine until normal;operating'tempenatures are @b1 v tained? and: i thereafter?operable;-y tonary: gradually'theirelatifsie Aproporl'ionsfoli hoti and cold; air to maintain -the'lair ladmittedto the' mixing-passage' at:` a proper tem-perature;.v This may bel'readily, accomplished',y by con-- necting' tof'the' fue'l'inlet section: a` thermostatic: control" for carhuretorst of the: type' disclosed in my prior Patent No. 1,627,941 grantedxMay '10,; 1921.1 carburetor control, comprises a tubular` 'll-'shaped casing' 138;: oneo the,` branches 139 of 'which xis tele scopicall-y mountedr-in' and secured'- tonthe. im let;'end. o'the inlet section 86, with' theother 'braenchz 140 'forming theif cold air'inlet'extend- Ico ing in theyopposite'direction'. -The het air' branch: 14h-extends: at right :angles 'to the' branches139 amdrllet); r`'lxliemeans 'forfchoka ing' the| hot' a'ir: inlet preferably comprises a thermostatically operableV-lve'142I of! the character' described! i-n `tile-'patent aforesaid which, upon'fcold'starting, isil'ocated.' approxitmately: inut'h'e choking position illustrated', andas the engifne'warms: up gradually rot.. tates' in ai clockwise direction. toward open positi'on/ and as the hotf'air from the engine increases beyond? a predetermined."'amountrota-tes beyond "vertical" position;` and acts gradually again tocholie the admissiony of hot arr.

The thermostati'cal-ly operable valve 142 has connected-tio it an arm- 143 which is coni nected by a link 144 to the arm 145 conthe initial opening movement of the thermostarting. Such manual choking mechanism statically controlled choke valve 142, during cold starting and warming u of the engine, has but little effect upon t e opening ofthe cold air valve 147, but as the thermostatically operable choke valve moves through and beyond vertical position the cold air Valve 147 is moved toward open position with relatively increasing rapidity.

Desirably the shaft 148 of the thermostatic valve is extended through the wall of the branch 141 and is rovided with an arm 1,49 the end of which is connected to a rod 150 leading to the instrument board, thereby pro' viding manualmeans for rotating the ther' mostatie choke valve further toward closed position than that which it normally assumes under the action of the thermostat.

In the operation of the device illustrated in Fig. 7, the operator may move the thermostatic choke valve 0f the hot air inlet to such choking position as to reduce a suction head upon the fuel inlet su ciently to supply the desired increased amount of fuel for cold may be immediately released upon the starting of the engine. Thereafter the proper suction head will be maintained by the action of the thermostat during the warming-up period ofthe engine, and also during changes in atmospheric temperature.`

By reason of this construction, as well as that illustrated in Figs. 1 to 4, a carburetor for an internal combustion en ine is-provided comprising a mixing passage aving a metering section, means for controlling the flow.

through the mixing passage, a fuel inlet communicating with said metering section and subject to a suction head substantially propor-4 tional to the suction head at the metering section, with means for delivering fuel through said inlet continuously at a low, predetermined rate during idle and light load operation of the engine to supplement the rate of flow induced by the suction head in the metering section, said fuel inlet and said controlling means being positioned lrelative to each other and co-ordinated with said mixingl passage in such a manneras to provide uninterrupted mixture flow from said fuel inlet and therebeyond incombination with regulating means acting on a single Afuel inlet to change the ratio of fuel to air supplied to the mixing passage. The advantage of the present invention, which employs'a low flowing head as compared with carburetor constructions in which the fuel is subject to a suction head at all times, is graphically shown in Fig. 10 in which ordinates represent' fuel-air ratio, and the abscissas representv loads from idle to full load. l

These curves are plotted from mathematical computations based upon the'fundamental flow laws'applying to fluids. From these curves it will be seen that below about 175 load they diverge rapidly, thus representing a low flowing head of 1A to 1/2 curving ad- .ually with increasing slope downwar y indicating an increase in the. richness of the 4 mixture as idle load is approached which is precisely what is desire representing an initial suction head of 1,41 to 1/2 rise rapidly indicating a leaning down of the mixture and soon reach a point where the mixture is so lean that engine operation is impossible without supplementary mechanism to supply the defect.

Actual tests on a carburetor constructed in accordance with the invention disclosed herein show that a flowing head of 1/4," or slightly less gives excellent operation andexcellent economy, indicatin that the curves here computed from the undamental flow laws are closely approximated.

Fig. 11 is a graphic illustration plotted in a similar manner with curves in broken lines showing the mixture requirements necessary to give maximumpower and maximumeiciency with a solid line superposed indicating the relative fuel-air A ratio distribution throughout the range of load of a carburetor constructed in accordance with the present invention.

- It will be observed that the curve showing the mixture ratio produced by the simple arrangement of parts in the present invention tion engine comprising a mixing passage while the curves.

www

mixing passage in such manner as to pro` duce uninterrupted mixture flow from vsaid fuel inlet and therebeyond, in combination with regulating means responsive to variations in temperature acting upon said fuel inlet to change the ratio of fuel and air supplied to-said mixing passage.

2. A carburetor. foran internal combustion engine` comprising -a mixing :passage having a metering section, means for controlling the flow through the mixing passage', a fuel inlet communicating with said meterinfr section and subject .to a suction head su stantially proportionalfto the suction head at said metering section, means to maintain continuously. a'ilow flowing head at said fuel inlet during idle and-light load operation of the engine to supplementv the rate of-flow induced by the suction head in the metering section, said fuel inlet and said controlling vmeans being positioned relatively to each other and co-ordinated with said mixing'passage in such manner as to pro'- duce uninterrupted mixture flow from vsaid 'fuel inlet and therebeyond, in. combination with regulating means respectively responsive to variations in temperature and barometric pressure acting on` said fuel inlet to change the ratio of fuel and air supplied to :said mixing passage.

3. Acar uretor for an internal'combustion engine comprising a mixing passage having a metering section, means for controlling the Howl-through the. mixing passage, a fuel inletcommunieatingvvith said meterin section and subject to a suction head su stantially proportional tothe suc- .tion head at said metering section, means to maintain continuously a low flowing head at said fuel inlet duringidle and light load operation of Ithe engine to supplement the rate of flow induced by the suction head in the metering section, said fuel inlet and said controlling means being positioned relatively to each other and co-ordinated with said mixing passage in such manner as to produce uninterrupted mixture flow from said fuel inlet and therebeyond, in combination with regulating means comprising a valve for said fuel inlet, thermostatic means within said passage engaging said valve, and pressure operable means outside of said passage acting to position said thermostatie means, and thereby change the ratio of fuel and air supplied to said mixing passage.

4. A. carburetor for an internal combustion engine comprising a mixing passage having an undivided section of its length extending downwardly, aV throttle valve in said mixing passage adapted to regulal. the tlow of mixture theretln-migh. and when at its idling position having itslower. portion in proximit)v to a portion ofthe wall of said undivided sect-ion. a fuel inlet passage romv,munieatmg with said undivided section of said mixing passage in --front of and above the lower portion of said throttlevalve, said fuel inlet passage having means to restrict a portion of its cross sectional area to form la fuel metering passage remaining constant .in area irrespective of changes in load-on the engine and through which all the fuel delivered to said mixing passage shall pass during idle and light load operations of the engine, in combination with means to maintain continuously a low flowing head at said `fuel metering section during idle andlight load operations of the engine to supplement the suctionl head induced by the suction existing at the dischargeend of said fuel inlet passage. Y f

5. A carburetor for an internal combustion engine com rising a mixing passage having anun'divi ed section of its length extending downwardly, a throttle valve in said mixing passa-ge adapted to regulate the flow of mixture therethrough, and when at its idling position having its lower portion in proximity to a portion of the wall of said undivided section, a fuel inlet passage communicating with said undivided section of said mixing passage in front of and above the lowerportion of said throttle valve, a fuel regulating valve in said fuel inlet passage adaptedv to remain in any desired adjusted position irrespective of changes in load on the engine and to control the effective area of said inlet passage through which all the fuel deliveredto the mixing passage shall pass during idle and light load operations of the'engine. in combination with means to maintain'continuously a. low flowing head at said fuel regulating valve during idle and light load operations of the engine to supplement the suction head induced by the suction existing at the discharge end of said fuel inlet passage. t

6. A carburetor for an internal combustionengine comprising an'lixing passage having an undivided section of its length extending downwardly, a throttle valve in .said mixing passage adapted to regulate the flow of mixture therethrough` and when at its idling position having its lower portion in proximity to a portion of the wall of said undivided section. a. fuel inlet passage communicating with said undivided section of said mixing passage in front of and above the. lower portion of said throttle valve.- said fuel inlet pas lill' head at said metering section, means for de- Alivering fuel= through said fuel inlet eontinuously during idle and light load operations of the engine ata low. redeterminedrate to supplement the-.rate o :flow induced by the suction fhead in saidrmetering section,Vl unitcontrolling means comprising v-a valveyfor said inlet, a pivotally.supported-thermostatic device engagingvsaid valve acting in response to increase in temperature to move the valve toward closed position, manual means .operable to open the valve temporarily, and means operable to maintain uninterrupted mixture iowirom said metering section and therebeyond during idle and" lightlfload operation as well 'as under heavy load.

' 8. A carburetorlfor aninternalicombustion engine comprising a-lmixing passagehaving a metering section, afuel 4inlet, l.communicating therewith subject ;;to a. suction head substantially proportional ito'rthe Asuction head at said metering section, means for deli-veriiig fuel through saidsfuel inlet` continuously during idle ,and light load operation; of the engine at a lowupredetermined rate to supplement the rate ofv ilowpinduced by the suction head `in said metering section, unit-controlling meanscomprising a valve for said .fuel inlet, an elastie-thermostatic element formed as a' return Ybend having the end oi one arm engaging-said valve, a pivotal support forA said thermostatic element, ad-

. justahle means initiallyato position said therinostatic element engaging the other arm thereof intermediate of lsaid pivot and said valve, elast-ic means exerting a tension on said valve in opposition to said thermostatic device, and means operable to maintain uninterrupted mixture fiow from said fuel inlet and therebeyond.

9. A. carburetor for an internal combiistion engine comprising a mixing passage having a metering section, a fuel inlet communicating therewith subject to a suction' head substantially proportional to the suction head at said metering section, means for delivering fuel through said fuel inlet continuously during idle and light load operation of the engine at a low predetermined rate to sul'iplement. the rate of flow induced by the suction head in said metering section, unit-controlling means comprising a valve slidable in said fuel inlet, an elastic thermostatic element having two substantially right angle bends forming a return bend and having the-end of one arm engaging said valve, a swinging pivotfor said tliermostatie eleinent acting to maintain one side of `said tion headsubstantially proportional to the suction head at said metering section, a valve -slidably mounted in said inlet having a wall complementary to a portion of the w-all of 'said inlet port, and means for maintaining the'same in` contact therewith, said valve being'cliamfered on 'the opposite side, means for delivering fuel through said fuel inlet during idleand light load operation of the engine at a. low, substantially constant, predetermined tlowing head, to supplement the rate -of flowinduced4 by the suction head in ysaid meteringsection, and means operable to maintain uninterrupted mixture flowl from said metering section and therebeyond during idle and light load operation' of the engine as wellas under heavy load.

11. A carburetor for an internal combustion engine comprising a mixing passage having a metering section, ay fuel inlet communicating therewith and subject to a suction head substantially proportional to the suction head in said metering section, a valve slidably mounted in said inlet having a wall complementary to the rip-stream wall of said inlet port, said valve being chanifered on the opposite side, a thermo-sensitiveJ device having means. acting tov maintain said comp1e mentary Walls iii Contact and operable to force said valve into said inlet, and elastic means exerting a tension on said valve in opposition to said therniostatic device, means for delivering fuel through said fuel inlet during idle and light load operation of the engine at a low, substantially constant, predetermined fiowing head to supplement the rate of flow induced by the suction head in said metering section. and means operable to maintain uninterrupted mixture flow from said metering section and thereheyond'during idle and light load operation of the engine as well as under heavyv load.

l2. A carburetor for an internal conduistioii engine.comprising ay mixing passage having an air metering section of substaninduced by the suction head in said metering section, and means located beyond and in proximity to said fuel inlet operable to maintain uninterruptedmixture flow beyond said fuel inlet. y

13. A carburetor for an internal combustion engine comprising a mixing passage having a metering section, a throttling valve with its lower end portion below and beyond said metering section, a fuel inlet positioned above the lower portion of said metering section and subject to a Suctionzhead substantially proportional to the suction head in said metering section, and means to maintain conti-nuously a low substantially constant flowing head' at said fuel inlet during idle and light load operation of the engine to supplement the rate of .flow induced by the suction head in said meterin' section.

14. A carburetor or an internal combustion engine comprising a mixing passage having a metering section, a throttlinfv valve with its lower end portion below and beyond said metering section, a fuel inlet positioned above the lower portion of said metering section and subject to a suction head substantially proportional to the suction lhead in said metering section, a fuel reservoirsurrounding said fuel inlet, a passage leading upwardly therefrom to said fuel inlet, and means for maintaining continuously during normal operation of the engine the liquid level in said reservoir at a height slightly above said fuel inlet.

15. A carburetor for an internal combustion engine comprising a mixing passage having a metering section` a throttling valve with its lower end portion below and beyond said metering section, a fuel inlet positioned above the lower portion of said metering sectionA and subject to a suction head substantially proportional to the suction head in said metering section, a fuel reservoir, surrounding said fuel inlet and communicating therewith, n'ieans for supplying fuel to said reservoir including a regulating valve, float sections in said reservoir symmetrically positioned relatively to said fuel inlet, lever mechanism intermediate of said float sections and said valve operable to transmit a sufcie-ntly tion engine comprising a mixing passage hav` ing a metering section, a throttling valve with its lower end portion below and 'beyond said metering section, a fuel inlet positioned above the lower portion of saidmetering section and subject to a suction head substantially proportional to the suction head in said metering section, and means tom'aintain continuously a low predetermined flowing h'ead at said fuel inlet to supplement the rate of flow induced byfthe suction head in said metering section during normal operation from approximately.. closed to half open position of said throttling valve, said throttling valve being arranged to reduce the effective arca of said metering section when moved from beyond half open position toward fullopen position.

c 18. A carburetor for an internalcombustionV engine having a mixing passage' provided with adepression intermediate ofv its length', a fuel inlet communicating with said passage infront of and above the lower portion of said depressiom-a fuel reservoir surrounding said fuelinlet and communicating therewith, and means for maintaining, continuously, the li uid level in said reservoir at a height slight y above said fuel inlet during idle and-light load operations of the engine, and means for throttling s'aid passage at said depression and below the level of said fuel inlet.y

19. A carburetor for an internal combustion engine comprising a mixing passave having relatively inclined inlet and outet sections forming at their junction a depression, a fuel inlet communicating with said inlet section above the lower portion of said depression, and means for throttling said passage beyond and below the level of said fuel inlet approximately at the junction of the outlet and inlet sections.'

20. A carburetor for an internal combustion engine having a mixing passage provided with a depression intermediate of its length and having a lrestricted port-ion which remains constant in area duringeidle and light load operations of the engine Ilocated in front of said depression, a fuel inlet com- `municating with said restricted portion, and

a. throttling valve in said passage with the lower portion thereof located beyond and below sald fuel inlet and so shaped and positioned that when approaching wide open position it will reduce the 4effective area of said restricted portion.

21. A carburetor for an internal combustion engine having a mixing passage provided With a depression intermediate of its length and having a restricted portion which remains consta-nt in area during idle and light load operations of the engine located in front of and adjacent to said depression, a fuel inlet communicating with said restricted portion, and a swinging throttle valve extending into said depression operable, when approaching full open position, to reduce the effective area of said restricted portion.

22. A carburetor for an internal combustion engine comprising a mixing passage having relatively inclined inlet and outlet sections forming at their junction a depression, said inlet sect-ion having a restricted portion which remains constant in area during idle and light load operations of tlie engine located in front of and adjacent to said depression, a fuel inlet communicating with said restricted portion, a fuel reservoir therefor surrounding said fuel inlet and said depression, a regulating valve slidablc in said fuel inlet having a wall complementary to the wall of said inlet and chamfered on the opposite side, tlieimostatic means in said passage controlling said regulating valve having means operable to maintain continuous light engagement between said complementary walls, without restraining theaction of the thermostatic means, and a throttlin g valve extending into said depression during idle and light load operations of the engine.

23. A carburetor for an internal combustion engine comprising a mixing passage having relatively inclined inlet and outlet sections forming at their junction a depression, said inlet section having a restricted `portion which remains constant in area during idle and light load operations of the engine located in front of and adjacent to said depression, a fuel inlet communicating with said restricted portion, a swinging throttle valve extending into said depression, during idle and light load operations of the engine, a reservoir surrounding said fuel inlet and communicating therewith, means to maintain, the liquid level in said reservoir slightly above said fuel inlet, controlling means comprising a valve for said inlet, thermnstatic means within said mixing passage engaging said valve, and means initially to position said thermostatic means.

24. A carburetor for an internal combustion engine comprising a mixing passage having relatively inclined inlet and outlet seotions forming at their junction a depression, said inlet section haring a restricted portion which remains constant in area during idle and light load operations of the engine lomunicating therewit means to maintain the liquid level in said reservoir slightly above said fuel inlet,.during idle and light load operations of the engine, controlling means comprising a valve for said inlet, thermostatic means within said passage engaging said valve, and pressure-operable means acting to positionsaid thermostatic means. 25. A carburetor for an internal combustion engine comprising a mixing passage having relatively inclined inlet and outlet sec-A tions forming at-their junction a depression,

said inlet section having a restricted portion which remains constant in area during idle and light load operations lof the engine located in front of andl adjacent to said depres-.- sion, a fuel inlet l,communicating with said restricted portion,';ffaV swinging throttle valve extending into said depression, during idle and light load operations of the engine, a reservoir surrounding said fuel inlet and communicating therewith, means to maintain the liquid level in saidreservoir slightly above said fuel inlet, during idle andlight load operations of the engine, controllin means comprising a valve for said inlet, a pivotally supported thermostastic device engaging said valve acting, in response to increase in temperature, to move the valvetoward closed position, and elastic means tending to move the valve toward open 'position against the resistance of said thermostatic device.

f 26. Al carburetor for an internal combustion engine comprising a mixing passage having relatively inclined inlet and outlet sections forming at their junction a depression, said inlet section having a restricted portion which remains constant in area during idle and light load operations' of the engine located in front of and adjacent to said depression, a fuel inlet communicating with said restricted portion, a swinging throttle valve extending into said depression, during idle and light load operations of the engine, a reservoir surrounding said fuel inlet and communicating therewith, means to maintain the liquid level in said reservoir slightly i above said fuel inlet, during idle and light load operations of the engine, controlling means comprising a valve slidable in said inlet, an lelastic thermostatic element having two substantially right angle bends forming a return bend and having the end of one arm engaging said valve, a strut pivotally mounted at one end and inclined away from the axis of the valve engaging said element at one of said right angle bends, and adjustable means initially to position said thermostatic element engaging the other arm intermediate ef the engaged bend and said vale,

and manual means operable to onen said valve againstl the resistance of said thermostatic element.

,In testimony whereof, I have signed my name to this specicaton.

MERL R. WOLFARD. 

